What is it about?
In boreal forests, short growing seasons, cold temperatures, and the presence of frozen ground (permafrost) limit tree growth. Climate warming can potentially enhance growth by increasing air and soil temperatures. Here we found reduced tree growth since the 1980s at southern latitudes and increased growth at higher, colder latitudes, at least until the 2000s. Our results showed that recent permafrost warming at the highest latitudes, where permafrost is more prevalent in the landscape, has caused significant stress in tree growth due to ground destabilization. Trees growing in unstable permafrost used their nutrient uptake to remain upright instead of increasing their growth. These findings indicate that boreal forests will not become more productive with climate warming and the resulting permafrost thaw.
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Why is it important?
Here, we evaluated for the first time, the effects of permafrost and climate variability on black spruce trees across a 650 km climatic and permafrost gradient in the boreal forests of the Northwest Territories, Canada. We used a unique dataset that combines historic records of climate conditions and seasonal permafrost thaw with tree growth records and the occurrence of tree leaning events.
Perspectives
This study showcases how changing ground conditions, mainly accelerated permafrost thaw, has led to reduced tree growth in Canada’s Northern boreal forests. Continued warming, could further reduce growth and carbon storage capacities in boreal forests.
Raquel Alfaro Sanchez
Northern Forestry Centre. Canadian Forest Service
Read the Original
This page is a summary of: Permafrost instability negates the positive impact of warming temperatures on boreal radial growth, Proceedings of the National Academy of Sciences, December 2024, Proceedings of the National Academy of Sciences,
DOI: 10.1073/pnas.2411721121.
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